Expandable fusion device and method of installation thereof

ABSTRACT

The present invention provides an expandable fusion device capable of being installed inside an intervertebral disc space to maintain normal disc spacing and restore spinal stability, thereby facilitating an intervertebral fusion. In one embodiment, the fusion device includes a body portion, a first endplate, and a second endplate, the first and second endplates capable of being moved in a direction away from the body portion into an expanded configuration or capable of being moved towards the body portion into an unexpanded configuration. The fusion device is capable of being deployed and installed in both configurations.

This patent application is a continuation application claiming priorityto U.S. patent application Ser. No. 13/451,286, filed Apr. 19, 2012,which is a continuation-in-part application claiming priority to U.S.patent application Ser. No. 13/440,158, filed Apr. 5, 2012, now issuedas U.S. Pat. No. 8,679,183, which is a continuation-in-part applicationof U.S. patent application Ser. No. 12/823,736, filed Jun. 25, 2010, nowissued as U.S. Pat. No. 8,685,098, and a continuation-in-partapplication claiming priority to U.S. patent application Ser. No.13/273,994, filed Oct. 14, 2011, which is a continuation of U.S. patentapplication Ser. No. 12/579,833, filed Oct. 15, 2009, now issued as U.S.Pat. No. 8,062,375, the entire contents of which are incorporated byreference.

FIELD OF THE INVENTION

The present invention relates to the apparatus and method for promotingan intervertebral fusion, and more particularly relates to an expandablefusion device capable of being inserted between adjacent vertebrae tofacilitate the fusion process.

BACKGROUND OF THE INVENTION

A common procedure for handling pain associated with intervertebraldiscs that have become degenerated due to various factors such as traumaor aging is the use of intervertebral fusion devices for fusing one ormore adjacent vertebral bodies. Generally, to fuse the adjacentvertebral bodies, the intervertebral disc is first partially or fullyremoved. An intervertebral fusion device is then typically insertedbetween neighboring vertebrae to maintain normal disc spacing andrestore spinal stability, thereby facilitating an intervertebral fusion.

There are a number of known conventional fusion devices andmethodologies in the art for accomplishing the intervertebral fusion.These include screw and rod arrangements, solid bone implants, andfusion devices which include a cage or other implant mechanism which,typically, is packed with bone and/or bone growth inducing substances.These devices are implanted between adjacent vertebral bodies in orderto fuse the vertebral bodies together, alleviating the associated pain.

However, there are drawbacks associated with the known conventionalfusion devices and methodologies. For example, present methods forinstalling a conventional fusion device often require that the adjacentvertebral bodies be distracted to restore a diseased disc space to itsnormal or healthy height prior to implantation of the fusion device. Inorder to maintain this height once the fusion device is inserted, thefusion device is usually dimensioned larger in height than the initialdistraction height. This difference in height can make it difficult fora surgeon to install the fusion device in the distracted intervertebralspace.

As such, there exists a need for a fusion device capable of beinginstalled inside an intervertebral disc space at a minimum to nodistraction height and for a fusion device that can maintain a normaldistance between adjacent vertebral bodies when implanted.

SUMMARY OF THE INVENTION

In an exemplary embodiment, the present invention provides an expandablefusion device capable of being installed inside an intervertebral discspace to maintain normal disc spacing and restore spinal stability,thereby facilitating an intervertebral fusion. In one embodiment, thefusion device includes a body portion, a first endplate, and a secondendplate. The first and second endplates are capable of being moved in adirection away from the body portion into an expanded configuration orcapable of being moved towards the body portion into an unexpandedconfiguration. The expandable fusion device is capable of being deployedand installed in the unexpanded configuration or the expandedconfiguration.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred or exemplary embodiments of the invention, areintended for purposes of illustration only and are not intended to limitthe scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a side view of an embodiment of an expandable fusion deviceshown between adjacent vertebrae according to the present invention;

FIG. 2 is an exploded view of the expandable fusion device of FIG. 1;

FIG. 3 is a front perspective view of the expandable fusion device ofFIG. 1 shown in an unexpanded position

FIG. 4 is a front perspective view of the expandable fusion device ofFIG. 1 shown in an expanded position;

FIG. 5 is a rear perspective view of the expandable fusion device ofFIG. 1 shown in an unexpanded position;

FIG. 6 is a rear perspective view of the expandable fusion device ofFIG. 1 shown in an expanded position;

FIG. 7 is a side view of the expandable fusion device of FIG. 1 shown inan unexpanded position;

FIG. 8 is a side view of the expandable fusion device of FIG. 1 shown inan expanded position;

FIG. 9 is a top view of the expandable fusion device of FIG. 1;

FIG. 10 is a side partial cross-sectional view of the expandable fusiondevice of FIG. 1 shown in an unexpanded position;

FIG. 11 is a side partial cross-sectional view of the expandable fusiondevice of FIG. 1 shown in an expanded position;

FIG. 12 is a side schematic view of the expandable fusion device of FIG.1 having different endplates;

FIG. 13 is a partial side schematic view of the expandable fusion deviceof FIG. 1 showing different modes of endplate expansion; and

FIG. 14 is a side schematic view of the expandable fusion device of FIG.1 with artificial endplates shown between adjacent vertebrae.

FIG. 15 is a side view of an embodiment of an expandable fusion deviceshown between adjacent vertebrae according to the present invention;

FIG. 16 is an exploded view of the expandable fusion device of FIG. 15;

FIG. 17 is a rear perspective view of the expandable fusion device ofFIG. 15 shown in an unexpanded position;

FIG. 18 is a side cross-sectional view of the expandable fusion deviceof FIG. 15 shown with one of the endplates removed;

FIG. 19 is a side partial cross-sectional view of the expandable fusiondevice of FIG. 15 shown in an unexpanded position;

FIG. 20 is a side partial cross-sectional view of the expandable fusiondevice of FIG. 15 shown in an expanded position;

FIG. 21 is a side schematic view of the expandable fusion device of FIG.15 having different endplates;

FIG. 22 is a partial side schematic view of the expandable fusion deviceof FIG. 15 showing different modes of endplate expansion;

FIG. 23 is a side schematic view of the expandable fusion device of FIG.15 with artificial endplates shown between adjacent vertebrae;

FIG. 24 is a side view cross-sectional view of another embodiment of anexpandable fusion device shown in an unexpanded position;

FIG. 25 is a side view cross-sectional view of the expandable fusiondevice of FIG. 24 shown in an expanded position;

FIG. 26 is a side view of the expandable fusion device of FIG. 24showing the translation member and the ramped insert;

FIG. 27 is a front perspective view of the expandable fusion device ofFIG. 24 showing the translation member and the ramped insert;

FIG. 28 is a rear perspective of another embodiment of an expandablefusion device with the endplates having a threaded hole;

FIG. 29 is a top view of another embodiment of an expandable fusiondevice shown in an unexpanded position;

FIG. 30 is a bottom view of the expandable fusion device of FIG. 29;

FIG. 31 is top view of the expandable fusion device of FIG. 29 shown inan expanded position;

FIG. 32 is an exploded perspective view of another embodiment of anexpandable fusion device;

FIG. 33 is an end view of the expandable fusion device of FIG. 32 in anunexpanded position;

FIG. 34 is an end view of the expandable fusion device of FIG. 32 in anexpanded position;

FIG. 35 is a perspective view of another embodiment of an expandablefusion device;

FIG. 36 is a top view of the expandable fusion device of FIG. 35;

FIG. 37 is a perspective view of the expandable fusion device of FIG. 35with a closed end.

FIG. 38 is a front view of the expandable fusion device of FIG. 37 shownbetween adjacent vertebrae in an unexpanded position; and

FIG. 39 is a front view of the expandable fusion device of FIG. 37 shownbetween adjacent vertebrae in an expanded position.

FIG. 40 is an exploded view of an alternative fusion device.

FIG. 41 is a top view of the device in FIG. 40 with a first endplateremoved.

FIG. 42 is a top view of the alternative fusion device having sidestabilization members.

FIG. 43 is a perspective view of the device in FIG. 42.

FIG. 44 is a side cross-sectional view of the device in FIG. 42.

FIG. 45 is a perspective view of a trial member in a non-expandedconfiguration.

FIG. 46 is a side cross-sectional view of the trial member of FIG. 45 inan expanded configuration.

FIG. 47 is a top view of the trial member.

FIG. 48 is an exploded view of the trial member.

FIG. 49 is a side cross-sectional view of a portion of an alternativefusion device incorporating a ring member therein.

FIG. 50 is a perspective view of a portion of the alternative fusiondevice of FIG. 49.

FIG. 51 is a side cross-sectional view of a proximal portion of a trialmember in an unlocked configuration.

FIG. 52 is a side cross-sectional view of a proximal portion of a trialmember in a locked configuration.

FIG. 53 is an alternate side cross-sectional view of a proximal portionof a trial member in a locked configuration.

FIG. 54 is a perspective cross-sectional view of a proximal portion of atrial member in a locked configuration.

FIG. 55 is a front cross-sectional view of a proximal portion of a trialmember.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

A spinal fusion is typically employed to eliminate pain caused by themotion of degenerated disk material. Upon successful fusion, a fusiondevice becomes permanently fixed within the intervertebral disc space.Looking at FIG. 1, an exemplary embodiment of an expandable fusiondevice 10 is shown between adjacent vertebral bodies 2 and 3. The fusiondevice 10 engages the endplates 4 and 5 of the adjacent vertebral bodies2 and 3 and, in the installed position, maintains normal intervertebraldisc spacing and restores spinal stability, thereby facilitating anintervertebral fusion. The expandable fusion device 10 can bemanufactured from a number of materials including titanium, stainlesssteel, titanium alloys, non-titanium metallic alloys, polymericmaterials, plastics, plastic composites, PEEK, ceramic, and elasticmaterials.

In an exemplary embodiment, bone graft or similar bone growth inducingmaterial can be introduced around and within the fusion device 10 tofurther promote and facilitate the intervertebral fusion. The fusiondevice 10, in one embodiment, is preferably packed with bone graft orsimilar bone growth inducing material to promote the growth of bonethrough and around the fusion device. Such bone graft may be packedbetween the endplates of the adjacent vertebral bodies prior to,subsequent to, or during implantation of the fusion device.

With reference to FIG. 2, an exploded perspective view of one embodimentof the fusion device 10 is shown. In an exemplary embodiment, the fusiondevice 10 includes a body portion 12, a first endplate 14, a secondendplate 16, a translation member 18, a plurality of pins 20, anactuation member 22, and a locking mechanism 24.

With additional reference to FIGS. 3-8, in an exemplary embodiment, thebody portion 12 has a first end 26, a second end 28, a first sideportion 30 connecting the first end 26 and the second end 28, and asecond side portion 32 connecting the first end 26 and the second end28. The body portion 12 further includes an upper end 34, which is sizedto receive at least a portion of the first endplate 14, and a lower end36, which is sized to receive at least a portion of the second endplate16.

The first end 26 of the fusion device 10, in an exemplary embodiment,includes at least one angled surface 38, but can include multiple angledsurfaces. The angled surface can serve to distract the adjacentvertebral bodies when the fusion device 10 is inserted into anintervertebral space. In another preferred embodiment, it iscontemplated that there are at least two opposing angled surfacesforming a generally wedge shaped to distract the adjacent vertebralbodies when the fusion device 10 is inserted into an intervertebralspace.

The second end 28 of the body portion 12, in an exemplary embodiment,includes an opening 40 which may include threading. In another exemplaryembodiment, the opening 40 may include ratchet teeth instead ofthreading. The opening 40 extends from the second end 28 of the bodyportion 12 into a central opening 42 in the body portion 12. In oneembodiment, the central opening 42 is sized to receive the translationmember 18 and the opening 40 is sized to threadingly receive theactuation member 22. In another exemplary embodiment, the opening 40 issized to receive the actuation member 22 in a ratcheting fashion. In yetanother exemplary embodiment, first side portion 30 and second sideportion 32 each include a recess 44 located towards the second end 28 ofthe body portion 12. The recess 44 is configured and dimensioned toreceive an insertion instrument (not shown) that assists in theinsertion of the fusion device 10 into an intervertebral space.

Although the following discussion relates to the first endplate 14, itshould be understood that it also equally applies to the second endplate16 as the second endplate 16 is substantially identical to the firstendplate 14. Turning now to FIGS. 2-11, in an exemplary embodiment, thefirst endplate 14 has an upper surface 46, a lower surface 48, and athrough opening 49. The through opening 49, in an exemplary embodiment,is sized to receive bone graft or similar bone growth inducing materialand further allow the bone graft or similar bone growth inducingmaterial to be packed in the central opening 42 in the body portion 12.

In one embodiment, the lower surface 48 includes at least one extension50 extending along at least a portion of the lower surface 48. As bestseen in FIGS. 2 and 4, in an exemplary embodiment, the extension 50 canextend along a substantial portion of the lower surface 48, including,along each side of the endplate 14 and along the front end of theendplate 14. In another exemplary embodiment, the extension 50 includesat least one slot 52, but can include any number of slots 52, includingtwo sets of slots 52 opposing each other, as best seen in FIG. 2. Theslots 52 are configured and dimensioned to receive pins 20 and areoriented in an oblique fashion. In another embodiment, the slots 52 maybe oriented in a generally vertical orientation.

In an exemplary embodiment, the extension 50 is sized to be receivedwithin the central opening 42 of the body portion 12. As best seen inFIGS. 11-12, the lower surface 48 of the first endplate 14 furtherincludes, in an exemplary embodiment, at least one ramped surface 54. Inanother exemplary embodiment, there are two spaced ramped surfaces 54,56. It is contemplated that the slope of the ramped surfaces 54, 56 canbe equal or can differ from each other. The effect of varying the slopesof the ramped surfaces 54, 56 is discussed below.

Referring now to FIGS. 2-9, in one embodiment, the upper surface 46 ofthe first endplate 14 is flat and generally planar to allow the uppersurface 46 of the endplate 14 to engage with the adjacent vertebral body2. Alternatively, as shown in FIG. 12, the upper surface 46 can becurved convexly or concavely to allow for a greater or lesser degree ofengagement with the adjacent vertebral body 2. It is also contemplatedthat the upper surface 46 can be generally planar but includes agenerally straight ramped surface or a curved ramped surface. The rampedsurface allows for engagement with the adjacent vertebral body 2 in alordotic fashion. Turning back to FIGS. 2-9, in an exemplary embodiment,the upper surface 46 includes texturing 58 to aid in gripping theadjacent vertebral bodies. Although not limited to the following, thetexturing can include teeth, ridges, friction increasing elements,keels, or gripping or purchasing projections.

With reference to FIGS. 2 and 10-11, in an exemplary embodiment, thetranslation member 18 is sized to be received within the central opening42 of the body portion 12 and includes at least a first expansionportion 60. In another embodiment, the translation member 18 includes afirst expansion portion 60 and a second expansion portion 62, theexpansion portions 60, 62 being connected together via a bridge portion68. It is also contemplated that there may be more than two expansionportions where each of the expansion portions is connected by a bridgeportion. The expansion portions 60, 62 each have angled surfaces 64, 66configured and dimensioned to engage the ramp surfaces 54, 56 of thefirst and second endplates 14, 16. In an exemplary embodiment, thetranslation member 18 also includes recesses 70, 72, the recesses 70, 72are sized to receive and retain pins 20. In one embodiment, theexpansion portion 60 includes an opening 74, which is sized to receive aportion of the actuation member 22, and the expansion portion 62includes a nose 76, which is received within an opening 78 in the firstend 26 to stabilize the translation member 18 in the central opening 42of the body member 12.

In an exemplary embodiment, the actuation member 22 has a first end 80,a second end 82 and threading 84 extending along at least a portionthereof from the first end 80 to the second end 82. The threading 84threadingly engages the threading extending along a portion of opening40 in the body portion 12. In another exemplary embodiment, theactuation member 22 includes ratchet teeth instead of threading. Theratchet teeth engage corresponding ratchet teeth in the opening 40 inthe body portion 12. The first end 80 includes a recess 86 dimensionedto receive an instrument (not shown) that is capable of advancing theactuation member 22 with respect to the body portion 12 of the fusiondevice 10. The second end 82 of the actuation member 22 includes anextension 88 that is received within the opening 74 of the expansionportion 60. In one embodiment, the extension 88 may include a pluralityof slits and a lip portion. The plurality of slits allows the extensionportion 88 to flex inwardly reducing its diameter when received in theopening 74. Once the lip portion of the extension portion 88 is advancedbeyond the end of the opening 74, the extension portion 88 will returnback to its original diameter and the lip portion will engage theexpansion portion 60. It is further contemplated that a pin member 90can be included to prevent the extension portion from flexing inwardlythereby preventing the actuation member 22 from disengaging from thetranslation member 18.

In an exemplary embodiment, the fusion device 10 can further include alocking mechanism 24. The mechanism 24 is designed to resist rotation ofthe actuation member 22 rather than prevent rotation of the actuationmember 22. In an exemplary embodiment, either deformable threading canbe included on actuation member 22 or a disruption of the threading maybe included where a deformable material is included in the threadingdisruption. It is contemplated that the deformable member or deformablethreading can be made from a deformable or elastic, biocompatiblematerial such as nitinol or PEEK.

Turning now to FIGS. 1-8 and 10-11, a method of installing theexpandable fusion device 10 is now discussed. Prior to insertion of thefusion device 10, the intervertebral space is prepared. In one method ofinstallation, a diskectomy is performed where the intervertebral disc,in its entirety, is removed. Alternatively, only a portion of theintervertebral disc can be removed. The endplates of the adjacentvertebral bodies 2, 3 are then scraped to create an exposed end surfacefor facilitating bone growth across the invertebral space. Theexpandable fusion device 10 is then introduced into the intervertebralspace, with the first end 26 being inserted first into the disc spacefollowed by the second end 28. In an exemplary method, the fusion device10 is in the unexpanded position when introduced into the intervertebralspace. The wedged shaped first end 26 will assist in distracting theadjacent vertebral bodies 2, 3 if necessary. This allows for the optionof having little to no distraction of the intervertebral space prior tothe insertion of the fusion device 10. In another exemplary method, theintervertebral space may be distracted prior to insertion of the fusiondevice 10. The distraction provide some benefits by providing greateraccess to the surgical site making removal of the intervertebral disceasier and making scraping of the endplates of the vertebral bodies 2, 3easier.

With the fusion device 10 inserted into and seated in the appropriateposition in the intervertebral disc space, the fusion device can thenexpanded into the expanded position, as best seen in FIGS. 1, 4, 6, 8,and 11. To expand the fusion device 10, an instrument is engaged withrecess 86 in the actuation member 22. The instrument is used to rotateactuation member 22. As discussed above, actuation member 22 isthreadingly engaged body portion 12 and is engaged with translationmember 18; thus, as the actuation member 22 is rotated in a firstdirection, the actuation member 22 and the translation member 18 movewith respect to the body portion 12 toward the first end 26 of the bodyportion 12. In another exemplary embodiment, the actuation member 22 ismoved in a linear direction with the ratchet teeth engaging as means forcontrolling the movement of the actuation member 22 and the translationmember 18. As the translation member 18 moves, the ramped surface 64, 66of the expansion portions 60, 62 push against the ramped surfaces 54, 56of the endplates 14, 16 pushing endplates 14, 16 outwardly into theexpanded position. This can best be seen in FIGS. 10 and 11. Since theexpansion of the fusion device 10 is actuated by a rotational input, theexpansion of the fusion device 10 is infinite. In other words, theendplates 14, 16 can be expanded to an infinite number of heightsdependent on the rotational advancement of the actuation member 22. Asdiscussed above, the fusion device 10 includes a locking mechanism 24which assists in retaining the endplates 14, 16 at the desired height.

It should also be noted that the expansion of the endplates 14, 16 canbe varied based on the differences in the dimensions of the rampedsurfaces 54, 56, 64, 66. As best seen in FIG. 13, the endplates 14, 16can be expanded in any of the following ways: straight rise expansion,straight rise expansion followed by a toggle into a lordotic expandedconfiguration, or a phase off straight rise into a lordotic expandedconfiguration.

Turning back to FIGS. 1-8 and 10-11, in the event the fusion device 10needs to be repositioned or revised after being installed and expanded,the fusion device 10 can be contracted back to the unexpandedconfiguration, repositioned, and expanded again once the desiredpositioning is achieved. To contract the fusion device 10, theinstrument is engaged with recess 86 in the actuation member 22. Theinstrument is used to rotate actuation member 22. As discussed above,actuation member 22 is threadingly engaged body portion 12 and isengaged with translation member 18; thus, as the actuation member 22 isrotated in a second direction, opposite the first direction, theactuation member 22 and translation member 18 move with respect to thebody portion 12 toward the second end 28 of the body portion 12. As thetranslation member 18 moves, the pins 20, a portion of which are locatedwithin the slots 52, ride along the slots 52 pulling the endplates 14,16 inwardly into the unexpanded position.

With reference now to FIG. 14, fusion device 10 is shown with anexemplary embodiment of artificial endplates 100. Artificial endplates100 allows the introduction of lordosis even when the endplates 14 and16 of the fusion device 10 are generally planar. In one embodiment, theartificial endplates 100 have an upper surface 102 and a lower surface104. The upper surfaces 102 of the artificial endplates 100 have atleast one spike 106 to engage the adjacent vertebral bodies. The lowersurfaces 104 have complementary texturing or engagement features ontheir surfaces to engage with the texturing or engagement features onthe upper endplate 14 and the lower endplate 16 of the fusion device 10.In an exemplary embodiment, the upper surface 102 of the artificialendplates 100 have a generally convex profile and the lower surfaces 104have a generally parallel profile to achieve lordosis. In anotherexemplary embodiment, fusion device 10 can be used with only oneartificial endplate 100 to introduce lordosis even when the endplates 14and 16 of the fusion device 10 are generally planar. The artificialendplate 100 can either engage endplate 14 or engage endplate 16 andfunction in the same manner as described above with respect to twoartificial endplates 100.

Although the preceding discussion only discussed having a single fusiondevice 10 in the intervertebral space, it is contemplated that more thanone fusion device 10 can be inserted in the intervertebral space. It isfurther contemplated that each fusion device 10 does not have to befinally installed in the fully expanded state. Rather, depending on thelocation of the fusion device 10 in the intervertebral disc space, theheight of the fusion device 10 may vary from unexpanded to fullyexpanded.

With reference to FIG. 16, an exploded perspective view of oneembodiment of the fusion device 210 is shown. In an exemplaryembodiment, the fusion device 210 includes a body portion 212, a firstendplate 214, a second endplate 216, a translation member 218, anactuation member 220, and an insert 222.

With additional reference to FIGS. 17-20, in an exemplary embodiment,the body portion 212 has a first end 224, a second end 226, a first sideportion 228 connecting the first end 224 and the second end 226, and asecond side portion 229 on the opposing side of the body portion 212connecting the first end 224 and the second end 226. The body portion212 further includes an upper end 230, which is sized to receive atleast a portion of the first endplate 214, and a lower end 232, which issized to receive at least a portion of the second endplate 216.

The first end 224 of the body portion 212, in an exemplary embodiment,includes at least one angled surface 234, but can include multipleangled surfaces. The angled surface 234 can serve to distract theadjacent vertebral bodies when the fusion device 210 is inserted into anintervertebral space. In another preferred embodiment, it iscontemplated that there are at least two opposing angled surfacesforming a generally wedge shaped to distract the adjacent vertebralbodies when the fusion device 210 is inserted into an intervertebralspace.

The second end 226 of the body portion 212, in an exemplary embodiment,includes an opening 236 which may include threading. In anotherexemplary embodiment, the opening 236 may include ratchet teeth insteadof threading. The opening 236 extends from the second end 226 of thebody portion 212 into a central opening (not illustrated) in the bodyportion 212. In one embodiment, the central opening is sized to receivethe translation member 218, and the opening 236 is sized to threadinglyreceive the actuation member 220. In another exemplary embodiment, theopening 236 is sized to receive the actuation member 220 in a ratchetingfashion. In yet another exemplary embodiment, first side portion 228 andsecond side portion 229 each include a recess 238 located towards thesecond end 226 of the body portion 212. The recess 238 is configured anddimensioned to receive an insertion instrument (not shown) that assistsin the insertion of the fusion device 210 into an intervertebral space.

Although the following discussion relates to the first endplate 214, itshould be understood that it also equally applies to the second endplate216 as the second endplate 216 is substantially identical to the firstendplate 214 in embodiments of the present invention. Turning now toFIGS. 16-20, in an exemplary embodiment, the first endplate 214 has anupper surface 240, a lower surface 242, and a through opening 243. Thethrough opening 243, in an exemplary embodiment, is sized to receivebone graft or similar bone growth inducing material and further allowthe bone graft or similar bone growth inducing material to be packed inthe central opening in the body portion 212.

In one embodiment, the lower surface 242 includes at least one extension244 extending along at least a portion of the lower surface 242. As bestseen in FIGS. 17 and 18, in an exemplary embodiment, the extension 244can extend along a substantial portion of the lower surface 242,including, along each side of the endplate 214 and along the front endof the endplate 214. In another exemplary embodiment, the extension 244includes at least one ramped portion 246, but can include any number oframped portions, including two spaced ramped portions 246, 248 in theextension 244 that extend between each side of the endplate 214, as bestseen in FIG. 18. It is contemplated that the slope of the rampedportions 246, 248 can be equal or can differ from each other. The effectof varying the slopes of the ramped portions 246, 248 is discussedbelow.

In an exemplary embodiment, the ramped portions 246, 248 further includegrooved portions 247, 249 that are configured and dimensioned to receiveangled surfaces 258, 260 of the translation member 218 and are orientedin an oblique fashion. In a preferred embodiment, the grooved portions246, 248 are dovetail grooves configured and dimensioned to hold theangled surfaces 258, 260 of the translation member 218 while allowingthe angles surfaces 258, 260 to slide against the ramped portions 246,248.

Referring now to FIGS. 17-20, in one embodiment, the upper surface 240of the first endplate 214 is flat and generally planar to allow theupper surface 240 of the endplate 214 to engage with the adjacentvertebral body 202. Alternatively, as shown in FIG. 21, the uppersurface 240 can be curved convexly or concavely to allow for a greateror lesser degree of engagement with the adjacent vertebral body 202. Itis also contemplated that the upper surface 240 can be generally planarbut includes a generally straight ramped surface or a curved rampedsurface. The ramped surface allows for engagement with the adjacentvertebral body 202 in a lordotic fashion. Turning back to FIGS. 16-20,in an exemplary embodiment, the upper surface 240 includes texturing 250to aid in gripping the adjacent vertebral bodies. Although not limitedto the following, the texturing can include teeth, ridges, frictionincreasing elements, keels, or gripping or purchasing projections.

With reference to FIGS. 16 and 18-20, in an exemplary embodiment, thetranslation member 218 is sized to be received within the centralopening of the body portion 212 and includes at least a first expansionportion 252. In another embodiment, the translation member 218 includesa first expansion portion 252 and a second expansion portion 254, theexpansion portions 252, 254 being connected together via a bridgeportion 256. It is also contemplated that there may be more than twoexpansion portions where each of the expansion portions is connected bya bridge portion. The expansion portions 252, 254 each have angledsurfaces 258, 260 configured and dimensioned to engage the groovedportions 246, 248 of the first and second endplates 214, 216. In oneembodiment, the translation member 218 includes an opening 262 in thefirst expansion portion 252, which is sized to receive a portion of theactuation member 220, as best seen in FIG. 18. In an exemplaryembodiment, the first expansion portion 252 includes a central bore 263that extends from the opening 262 and through the first expansionportion 252. In one embodiment, the translation member 218 includes ahole 264 in the second expansion portion 254, which is sized to receivenose 266, as best seen in FIGS. 19 and 20. In an exemplary embodiment,the hole 264 includes threading 268 for threadedly receiving a threadedend 270 of the nose 266, as shown on FIG. 20. The nose 266 is receivedin an opening 272 in the first end 234 of the body portion 212 tostabilize the translation member 218 in the central opening of the bodyportion 212.

In one embodiment, the translation member 218 includes a lockingmechanism 274, which is configured and adapted to engage the actuationmember 220. As illustrated, the locking mechanism 274 may extend fromthe first expansion portion 252. The locking mechanism 274 includes aslot 276 configured and adapted to receive extension 287 of theactuation member 220. In an exemplary embodiment, the locking mechanism274 further includes a stop 278 (e.g., a rim, a lip, etc.) that engagesthe actuation member 220 when it is disposed in the slot 276.

Referring now to FIGS. 16-20, in an exemplary embodiment, the actuationmember 220 has a first end 280, a second end 282, and threading (notillustrated) extending along at least a portion thereof from the firstend 280 to the second end 282. The threading threadingly engages thethreading that extends along a portion of opening 236 in the bodyportion 212. In another exemplary embodiment, the actuation member 220includes ratchet teeth instead of threading. The ratchet teeth engagecorresponding ratchet teeth in the opening 236 in the body portion 212.The first end 280 includes a recess 284 dimensioned to receive aninstrument (not shown) that is capable of advancing the actuation member220 with respect to the body portion 212 of the fusion device 210. In anembodiment, the actuation member 220 includes a bore 285, as best seenby FIG. 18, that extends from the recess 284 in the first end to thesecond 282. The second end 282 of the actuation member 220 includes anextension 286 that is received within the opening 262 in the firstexpansion portion 252. In one embodiment, the extension 288 may includea lip portion 286 and a plurality of slits 288. The plurality of slits288 are configured to receive inserts 222. Inserts 222 are provided tolimit motion of the actuation member 220. Once the lip portion 286 isplaced into the slot 276 of the locking mechanism 274, the lip portion286 will engage the stop 278 preventing longitudinal movement of theactuation member 220 with respect to the translation member 218. It isfurther contemplated that a pin member 290 can be included to furthersecure the actuation member 220 in the translation member 219. In anembodiment, the pin member 290 can be pressed into the central bore 285of the actuation member 220 and the central bore 263 of the translationmember, thereby preventing the actuation member 220 from disengagingfrom the translation member 218. Additionally, in an exemplaryembodiment, the fusion device 210 can further include a chamfered tip224 for distraction of adjacent vertebrae.

Turning now to FIGS. 15-20, a method of installing the expandable fusiondevice 210 is now discussed. Prior to insertion of the fusion device210, the intervertebral space is prepared. In one method ofinstallation, a discectomy is performed where the intervertebral disc,in its entirety, is removed. Alternatively, only a portion of theintervertebral disc can be removed. The endplates of the adjacentvertebral bodies 202, 203 are then scraped to create an exposed endsurface for facilitating bone growth across the invertebral space. Theexpandable fusion device 210 is then introduced into the intervertebralspace, with the first end 222 of the body portion 212 being insertedfirst into the disc space followed by the second end 224. In anexemplary method, the fusion device 210 is in the unexpanded positionwhen introduced into the intervertebral space. The wedged-shaped firstend 222 should assist in distracting the adjacent vertebral bodies 202,203, if necessary. This allows for the option of having little to nodistraction of the intervertebral space prior to the insertion of thefusion device 210. In another exemplary method, the intervertebral spacemay be distracted prior to insertion of the fusion device 210. Thedistraction provide some benefits by providing greater access to thesurgical site making removal of the intervertebral disc easier andmaking scraping of the endplates of the vertebral bodies 202, 203easier.

With the fusion device 210 inserted into and seated in the appropriateposition in the intervertebral disc space, the fusion device can thenexpanded into the expanded position, as best seen in FIGS. 15, 19, and20. To expand the fusion device 210, an instrument is engaged withrecess 284 in the actuation member 220. The instrument is used to rotateactuation member 220. As discussed above, actuation member 220 can bethreadingly engaging body portion 212 and is engaged with translationmember 218; thus, as the actuation member 220 is rotated in a firstdirection, the actuation member 220 and the translation member 218 movewith respect to the body portion 212 toward the first end 222 of thebody portion 212. In another exemplary embodiment, the actuation member220 is moved in a linear direction with the ratchet teeth engaging asmeans for controlling the movement of the actuation member 220 and thetranslation member 218. As the translation member 218 moves, the angledsurfaces 258, 260 of the expansion portions 252, 254 push against theramped portions 246, 248 of the endplates 214, 216 pushing endplates214, 216 outwardly into the expanded position with the angled surfaces258, 260 riding along the grooved portions 247, 248 of the rampedportions 246, 248. This can best be seen in FIGS. 19 and 20. Since theexpansion of the fusion device 210 is actuated by a rotational input,the expansion of the fusion device 210 is infinite. In other words, theendplates 214, 216 can be expanded to an infinite number of heightsdependent on the rotational advancement of the actuation member 220. Asdiscussed above, the fusion device 210 includes a locking mechanism 222which assists in retaining the endplates 14, 16 at the desired height.

It should also be noted that the expansion of the endplates 214, 216 canbe varied based on the differences in the dimensions of the rampedportions 246, 2 48 and the angled surfaces 258, 260. As best seen inFIG. 22, the endplates 214, 216 can be expanded in any of the followingways: straight rise expansion, straight rise expansion followed by atoggle into a lordotic expanded configuration, or a phase off straightrise into a lordotic expanded configuration.

Turning back to FIGS. 15-20, in the event the fusion device 210 needs tobe repositioned or revised after being installed and expanded, thefusion device 210 can be contracted back to the unexpandedconfiguration, repositioned, and expanded again once the desiredpositioning is achieved. To contract the fusion device 210, theinstrument is engaged with recess 284 in the actuation member 220. Theinstrument is used to rotate actuation member 220. As discussed above,actuation member 220 can be threadingly engaging body portion 212 and isengaged with translation member 218; thus, as the actuation member 220is rotated in a second direction, opposite the first direction, theactuation member 220 and translation member 218 move with respect to thebody portion 212 toward the second end 226 of the body portion 212. Asthe translation member 218 moves, the angled surfaces 258, 260 of thetranslation member 218 ride along the grooved portions 247, 249 pullingthe endplates 214, 216 inwardly into the unexpanded position.

With reference now to FIG. 23, fusion device 210 is shown with anexemplary embodiment of artificial endplates 300. Artificial endplates300 allows the introduction of lordosis even when the endplates 214 and216 of the fusion device 210 are generally planar. In one embodiment,the artificial endplates 300 have an upper surface 302 and a lowersurface 304. The upper surfaces 302 of the artificial endplates 300 haveat least one spike 306 to engage the adjacent vertebral bodies. Thelower surfaces 304 have complementary texturing or engagement featureson their surfaces to engage with the texturing or engagement features onthe upper endplate 214 and the lower endplate 216 of the fusion device210. In an exemplary embodiment, the upper surface 302 of the artificialendplates 300 have a generally convex profile and the lower surfaces 304have a generally parallel profile to achieve lordosis. In anotherexemplary embodiment, fusion device 210 can be used with only oneartificial endplate 300 to introduce lordosis even when the endplates214 and 216 of the fusion device 210 are generally planar. Theartificial endplate 300 can either engage endplate 214 or engageendplate 216 and function in the same manner as described above withrespect to two artificial endplates 300.

Referring now to FIGS. 24 and 25, an alternative embodiment of thefusion device 210 is shown. In an exemplary embodiment, the fusiondevice 210 includes a body portion 212, a first endplate 214, a secondendplate 216, a translation member 218, and an actuation member 220. Inthe illustrated embodiment, the fusion device further includes a firstramped insert 320 and a second ramped insert 322.

Although the following discussion relates to the first ramped insert320, it should be understood that it also equally applies to the secondramped insert 322 as the second ramped insert 322 is substantiallyidentical to the first ramped insert 320 in embodiments of the presentinvention. Turning now to FIGS. 24-27, in an exemplary embodiment, thefirst ramped insert 320 includes a first ramped portion 324 and a secondramped portion 326, the first and second ramped portions 324, 326 beingconnected by a bridge portion 328. The ramped portions 324, 326 eachhave grooved portions 330, 332 configured and dimensioned to receiveangled surfaces 258, 260 of the translation member. The ramped portions324, 326 can be oriented in an oblique fashion, as illustrated. In apreferred embodiment, the grooved portions 330, 332 are dovetail groovesconfigured and dimensioned to hold the angled surfaces 258, 260 of thetranslation member 218 while allowing the angles surfaces 258, 260 toslide against the ramped portions 324, 326.

In an exemplary embodiment, the first ramped insert 320 should beconfigured and dimensioned to be engaged with the first endplate 214. Inan embodiment, the first and second ramped portions 324, 326 includesnap connectors 334, 336 for securing the first ramped insert 320 to thefirst endplate. It should be understood that the snap connectors 334,336 are merely illustrative and that other suitable mechanisms forsecuring the first ramped inserted 320 with the first endplate 214 maybe used.

Referring to FIGS. 24-27, in an exemplary embodiment, the translationmember 218 is sized to be received within the central opening of thebody portion 212 and includes at least a first expansion portion 252. Inanother embodiment, the translation member 218 includes a firstexpansion portion 252 and a second expansion portion 254, the expansionportions 252, 254 being connected together via a bridge portion 256. Itis also contemplated that there may be more than two expansion portionswhere each of the expansion portions is connected by a bridge portion.The expansion portions 252, 254 each have angled surfaces 258, 260configured and dimensioned to engage the grooved portions 330, 332 ofthe first and second ramped inserts 320, 322. In one embodiment, theangled surfaces 258, 260 include corresponding grooved portions 338,340, as best seen in FIG. 27, that slidingly engaged the groovedportions 330, 332 of the first and second ramped inserts 320, 322.

In one embodiment, the expansion portion 252 includes an opening 262,which is sized to receive a portion of the actuation member 220, and theexpansion portion 262 includes a nose 266, which is received within anopening 272 in the first end 234 of the body portion 212 to stabilizethe translation member 218 in the central opening of the body portion212. In an embodiment, the nose 266 is integral with the expansionportion 262. In an embodiment (shown on FIGS. 16 and 18-20), the nose266 is threadingly engaged with the expansion portion 262. In anembodiment, the translation member 218 includes a locking mechanism 274to engage the actuation member 220, as illustrated in FIGS. 16-20.However, it should be understood that other suitable mechanisms may beused to secure the actuation member 220 within the translation member218. For example, the actuation member 220 may include an extension 287having a lip portion 286 (shown on FIGS. 16 and 18-20) that engages theexpansion portion 262. The extension 287 may, for example, be configuredto flex inwardly reducing its diameter when received in the opening 262.Once the lip portion 286 of the extension 287 is advanced beyond the endof the opening 262, the extension portion 287 will return back to itsoriginal diameter and the lip portion 286 will engage the expansionportion 260.

The expandable fusion device 210 of FIGS. 24-27 can be inserted into theintervertebral space in a manner similar to that the previouslydescribed with respect to FIGS. 15-20. After insertion, the expandablefusion device 210 of FIGS. 24-27 can be expanded into the expandedposition, as best seen in FIGS. 24 and 25. To expand the fusion device210, an instrument is engaged with recess 284 in the actuation member220. The instrument is used to rotate actuation member 220. As discussedabove, actuation member 220 can be threadingly engaging body portion 212and is engaged with translation member 218; thus, as the actuationmember 220 is rotated in a first direction, the actuation member 220 andthe translation member 218 move with respect to the body portion 212toward the first end 222 of the body portion 212. In another exemplaryembodiment, the actuation member 220 is moved in a linear direction withthe ratchet teeth engaging as means for controlling the movement of theactuation member 220 and the translation member 218. As the translationmember 218 moves, the angled surfaces 258, 260 of the expansion portions252, 254 push against the ramped portions 324, 326 of the first andsecond ramped inserts 320, 322 while riding along the grooved portions330, 332, thus pushing first and second ramped inserts 320, 322outwardly. Because the first and second ramped inserts 320, 322 areengaged with the endplates 214, 216, the endplates 214, 216 are alsopushed outwardly into the expanded position.

After expansion, the expandable fusion device 210 can be contracted backto the unexpanded configuration. To contract the fusion device 210, theinstrument is engaged with recess 284 in the actuation member 220. Theinstrument is used to rotate actuation member 220. As discussed above,actuation member 220 can be threadingly engaging body portion 212 and isengaged with translation member 218; thus, as the actuation member 220is rotated in a second direction, opposite the first direction, theactuation member 220 and translation member 218 move with respect to thebody portion 212 toward the second end 226 of the body portion 212. Asthe translation member 218 moves, the angled surfaces 258, 260 of thetranslation member 218 ride along the grooved portions 330, 332 pullingthe first and second ramped inserts 320, 322 and thus, the endplates214, 216 inwardly into the unexpanded position.

Referring now to FIG. 28, an alternative embodiment of the fusion device210 is shown. In an exemplary embodiment, the first endplate 214 and thesecond endplate 216 each include additional geometry to help securelyhold the endplates 214, 216 in place. In an embodiment, the firstendplate 214 and/or the second endplate 216 include threaded holes 341through which the fasteners, such as screws 342, may be inserted. In anembodiment, the threaded holes 341 penetrate through the first endplate214 and/or the second endplate 216 in an oblique fashion. It iscontemplated that the screws 342 may inserted through the threaded holes341 and into adjacent vertebral bodies 202, 203, to further secure thefirst endplate 214 and the second endplate 216 to the vertebral bodies202, 203. In some embodiments, these fasteners may be removed once amore long-term interface has been established, or alternatively thefasteners may remain in place indefinitely or until the fusion device210 needs adjustment and/or replacement.

With reference now FIGS. 29-31, an alternative embodiment of the fusiondevice 210 is shown that expands laterally. Lateral expansion maximizescoverage of the intravertebral disc space for wider load distributionand stability providing a rigid foundation for fusion. In oneembodiment, the fusion device 210 includes body portion 212, firstendplate 344, and second endplate 346.

Although the following discussion relates to the first endplate 344, itshould be understood that it also equally applies to the second endplate346 as the second endplate 346 is substantially identical to the firstendplate 344 in embodiments of the present invention. Turning now toFIGS. 31-33, in an exemplary embodiment, the first endplate 344 has anupper surface 348, a lower surface 350, and an inner surface 351 facingthe body portion 212. It is contemplated that the upper surface 348 willengage adjacent vertebral body 202 (seen on FIG. 15) and the lowersurface 350 will engage adjacent vertebral body 203 (seen on FIG. 15).In one embodiment, the upper surface 348 and the lower surface 350 areeach flat and generally planar to allow the upper surface 348 to engagewith the adjacent vertebral body 203. Alternatively, the upper surface348 and/or the lower surface 350 can be curved convexly or concavely toallow for a greater or lesser degree of engagement with the adjacentvertebral bodies 202, 203. It is also contemplated that the uppersurface 348 and/or the lower surface 350 can be generally planar butincludes a generally straight ramped surface or a curved ramped surface.The ramped surface allows for engagement with the adjacent vertebralbody 202 and/or the adjacent vertebral body 203 in a lordotic fashion.In an exemplary embodiment, the upper surface 348 and/or lower surface350 includes textures 352 to aid in gripping the adjacent vertebralbodies. Although not limited to the following, the texturing can includeteeth, ridges, friction increasing elements, keels, or gripping orpurchasing projections.

In one embodiment, the inner surface 351 includes at least one extension354 extending along at least a portion of the inner surface 351. In anexemplary embodiment, the extension 354 can extend along a substantialportion of the inner surface 354, including, along each side of theendplate 344 and along the front end of the endplate 214. While notillustrated, the inner surface may include ramped surfaces and groovedportions in an exemplary embodiment. It is contemplated that the rampedsurfaces and/or grooved portions may be similar to the ramped surfaces246, 248 and grooved portion 247, 249 in extension 244 shown on FIGS.18-20. In an embodiment, the extension 354 may include slots 356oriented in an oblique fashion through which pins 358 may be inserted.

While not illustrated, the fusion device 210 further includes featuresto effectuate the lateral expansion of the first and second endplates344, 346. In one embodiment, the fusion device 210 using a rampingsystem—similar to the system illustrated in FIGS. 16 and 18-20—forexpanding the first and second endplates 344, 346. In an exemplaryembodiment, the fusion device 210 further includes a translation memberand actuation member, such as translation member 218 and actuationmember 220 shown on FIGS. 16 and 18-20. It is contemplated that thetranslation member may include angled surfaces that push against rampedsurfaces in the extension 354, expanding the first and second endplates344, 346 outwardly and away from the body portion 212. In an embodiment,pins 356 disposed through the slots 354 may be retained in thetranslation member. In an alternative embodiment, dovetailing may beused for engagement of the angled surfaces and ramped surfaces. Itshould be understood that the translation member and actuation member inthis embodiment may be similar to the translation member 218 andactuation member 220 described above with respect FIGS. 15-20. Inanother embodiment, the fusion device 210 further includes first andsecond ramped inserts that are secured within the first and secondendplates 344, 346. The first and second ramped inserts may be similarto the first and second ramped inserts 320, 322 described above withrespect to FIGS. 24-27. It is contemplated that angled surfaces in thetranslation member may push against ramped surfaces in the rampedinserts pushing the ramped inserts outwardly. Because of theirengagement with the first and second endplates 344, 346, the first andsecond endplates 344, 346 may thus be expanded outwardly. In thismanner, the first and second endplates 344, 346 may be laterallyexpanded away from the body portion 212. It should be understood thatother suitable techniques may also be used to effectuate this lateralexpansion.

With reference to FIG. 32, an exploded perspective view of anotherembodiment of fusion device 210 is shown. In an exemplary embodiment,the fusion device 210 includes a body portion 212, a first endplate 400,a second endplate 402, a third endplate 404, a fourth endplate 406, anda translation member 218. In this embodiment, the fusion device 210 isconfigured to expand both vertically and laterally.

In an exemplary embodiment, the body portion 212 has a first end 224, asecond end 226, a first side portion 228 connecting the first end 224and the second end 226, and a second side portion 229 on the opposingside of the body portion 212 connecting the first end 224 and the secondend 226. The body portion 212 further includes a top side portion 408connecting the first end 224 and the second end 226, and a bottom sideportion 410 on the opposing side of the body portion 212 connecting thefirst end 224 and the second end 226. The body portion 212 furtherincludes first gap 412 between the top side portion 408 and the firstside portion 228, which is sized to receive at least a portion of thefirst endplate 400. The body portion 212 further includes second gap 414between the top side portion 408 and the second side portion 229, whichis sized to receive at least a portion of the second endplate 402. Thebody portion 212 further includes third gap 416 between the bottom sideportion 410 and the first side portion 228, which is sized to receive atleast a portion of the third endplate 404. The body portion 212 furtherincludes fourth gap 418 between the bottom side portion 410 and thesecond side portion 229, which is sized to receive at least a portion ofthe fourth endplate 406.

The first end 224 of the body portion 212, in an exemplary embodiment,includes an opening 420. The opening 420 extends from the first end 224of the body portion 212 into a central opening 422. In one embodiment,the central opening 422 is sized to receive the translation member 218.The second end 226 of the body portion 212, in an exemplary embodiment,includes an opening 236, which extends from the second end 226 of thebody portion 212 into the central opening 422.

Although the following discussion relates to the first endplate 400, itshould be understood that it also equally applies to the second endplate402, the third endplate 404, and the fourth endplate 406, as theseendplates 402, 404, 406 are substantially identical to the firstendplate 400 in embodiments of the present invention. Turning now toFIGS. 32-34, in an exemplary embodiment, the first endplate 214 has afirst end 424 and a second end 426. The first endplate further includesan upper surface 240 connecting the first end 424 and the second end 426and a lower surface 442 on an opposing side of the endplate 400connecting the first end 424 and the second end 426. While notillustrated, the first endplate 214 may include a through opening sizedto receive bone graft or similar bone growth inducing material andfurther allow the bone graft or similar bone growth inducing material tobe packed in the central opening 422 in the body portion 212.

In one embodiment, the lower surface 242 includes at least one firstretaining socket 428 on the lower surface 242. In an exemplaryembodiment, the lower surface 242 includes a first retaining socket 428at the interior corner of the intersection of the first end 424 and thelower surface 242, and a second retaining socket 430 at the interiorcorner of the intersection of the first end 424 and the lower surface242.

Referring now to FIGS. 32-34, in one embodiment, the upper surface 240of the first endplate 400 is curved convexly. Alternatively, the uppersurface 240 is flat or curved concavely to allow for a greater or lesserdegree of engagement with the adjacent vertebral body 202. It is alsocontemplated that the upper surface 240 can be generally planar butincludes a generally straight ramped surface or a curved ramped surface.The ramped surface allows for engagement with the adjacent vertebralbody 202 in a lordotic fashion. In an exemplary embodiment, the uppersurface 240 includes texturing 250 to aid in gripping the adjacentvertebral bodies. Although not limited to the following, the texturingcan include teeth, ridges, friction increasing elements, keels, orgripping or purchasing projections.

With reference to FIG. 32, in an exemplary embodiment, the translationmember 218 is sized to be received within the central opening 422 of thebody portion 212. The translation member 218 should be sized to allowlongitudinal translation within the central opening 422. In anembodiment, the translation member 218 includes at least a firstexpansion portion 252. In another embodiment, the translation member 218includes a first expansion portion 252 and a second expansion portion254, the expansion portions 252, 254 being connected together via abridge portion 256. It is also contemplated that there may be more thantwo expansion portions where each of the expansion portions is connectedby a bridge portion. The expansion portions 252, 254 each have angledsurfaces 258, 260. In an embodiment, the angles surfaces 258, 260 eachcomprise first end 429 and second end 431 with second end 431 beingwider than the first end 429. In an exemplary embodiment, the expansionportions 252, 254 include grooved portions 432, 434 on the edges of atleast two sides (e.g., the lateral sides) of the angled surfaces 258,260. The grooved portions 432, 434 are configured and dimensioned toengage the first and second retaining sockets 428, 430 on the endplates400, 402, 404, 406. In an exemplary embodiment, the grooved portions432, 434 retain the first and second retaining sockets 428, 430 insliding engagement.

In one embodiment, the translation member 218 includes a first end 436and a second end 438. The first end 436 of the translation memberincludes an extension 440 sized to be received within the opening 420 inthe first end 224 of the body portion 212. While not illustrated, thesecond end 438 also can include a similar extension sized to be receivedwithin opening 232 in the second end 226 of the body portion 212.

The expandable fusion device 210 of FIGS. 32-34 can be inserted into theintervertebral space in a manner similar to that the previouslydescribed with respect to FIGS. 15-20. After insertion, the expandablefusion device 210 of FIGS. 32-34 can be expanded into the expandedposition. As previously mentioned, the fusion device 210 shown on FIGS.32-34 expands both vertically and laterally. To expand the fusion device210, the translation member 218 can be moved with respect to the bodyportion 212 toward the first end 224 of the body portion. An instrumentcan be used, in an exemplary embodiment. As the translation member 218moves, the first retaining socket 428 and the second retaining socket430 ride along the grooved portions 432, 434 of the expansion portions252, 254 pushing the endplates 400, 402, 404, 406 outwardly in thedirection indicated by arrows 442. In an embodiment, the endplates 400,402, 404, 406 move outwardly in an oblique fashion to expand the fusiondevice 210 both vertically and laterally. The expanded configuration ofthe expansion device 210 is best seen in FIG. 34.

After expansion, the expandable fusion device 210 can be contracted backto the unexpanded configuration. The unexpanded configuration of thefusion device 210 is best seen in FIG. 34. To contract the fusion device210, the translation member 218 is moved with respect to the bodyportion 212 toward the second end 226 of the body portion 212. As thetranslation member 218 moves, the first retaining socket 428 and thesecond retaining socket 430 ride along the grooved portions 432, 434 ofthe expansion portions 252, 254 pulling the endplates 400, 402, 404, 406inwardly in a direction opposite that indicated by arrows 442. In anembodiment, the endplates 400, 402, 404, 406 move inwardly in an obliquefashion to contract the fusion device 210 both vertically and laterally.The unexpanded configuration of the expansion device 210 is best seen inFIG. 33.

With reference to FIGS. 35-36, another embodiment of expandable fusiondevice 210 is shown. In an exemplary embodiment, the fusion device 210includes a body portion 212, a vertically expanding plate 500, and agear 502. In this embodiment, a portion of the fusion device 210 isconfigured to expand vertically in at least one direction. In anexemplary embodiment, the vertically expanding plate 500 is configuredto expand outwardly from the body portion 212. It is contemplated thatan expandable fusion device 210 may be used to correct spinal curvaturedue to, for example, scoliosis, lordosis, and the like.

In an exemplary embodiment, the body portion 212 has a first end 224, asecond end 226, a first side portion 228 connecting the first end 224and the second end 226, and a second side portion 229 on the opposingside of the body portion 212 connecting the first end 224 and the secondend 226. The first end 224 of the body portion 212, in an exemplaryembodiment, includes at least one angled surface 234, but can includemultiple angled surfaces. The angled surface 234 can serve to distractthe adjacent vertebral bodies when the fusion device 210 is insertedinto an intervertebral space. In another preferred embodiment, it iscontemplated that there are at least two opposing angled surfacesforming a generally wedge shaped to distract the adjacent vertebralbodies when the fusion device 210 is inserted into an intervertebralspace. In yet another preferred embodiment, first side portion 228 andsecond side portion 229 each include a recess 238 located towards thesecond end 226 of the body portion 212. The recess 238 is configured anddimensioned to receive an insertion instrument 504 that assists in theinsertion of the fusion device 210 into an intervertebral space.

In an exemplary embodiment, the body portion 212 includes an upperengagement surface 506 extending from the first end 224 towards thesecond end 226, and a lower engagement surface 508 extending between thefirst end 224 and the second end 226. In an embodiment, the upperengagement surface 506 has a through opening 510. Although notillustrated, the lower engagement surface 508 may have a through openingthat is similar to through opening 510. The through opening 510, in anexemplary embodiment, is sized to receive bone graft or similar bonegrowth inducing material and further allow the bone graft or similarbone growth inducing material to be packed in the central opening in thebody portion 212. In an embodiment, at least a portion of the bodyportion 212 is removed to form a landing 512 in the body portion 212. Inan exemplary embodiment, a portion of the upper engagement surface 506and the second end 226 are removed to form the landing 512 having anupper surface 514. While not illustrated, a portion of the lowerengagement surface 508 and the second end 226 may be cut away, in analternative embodiment, to form the landing 512.

In one embodiment, the upper engagement surface 506 and the lowerengagement surface 508 are flat and generally planar to allow engagementsurfaces 506 to engage with the adjacent vertebral body 202 and thelower engagement surface 508 to engage with the adjacent vertebral body203. Alternatively, the upper engagement surface 506 and/or the lowerengagement surface 508 can be curved convexly or concavely to allow fora greater or lesser degree of engagement with the adjacent vertebralbodies 202, 203. In an exemplary embodiment, the upper engagementsurface 506 and/or the lower engagement surface includes texturing 512to aid in gripping the adjacent vertebral bodies. Although not limitedto the following, the texturing can include teeth, ridges, frictionincreasing elements, keels, or gripping or purchasing projections.

In an exemplary embodiment, vertically expanding plate 500 is coupled toan end of threaded bolt 518, which is coupled to the gear 502. In oneembodiment, the threaded bolt 518 is in threaded engagement with thegear 502. In an alternative embodiment, a bolt having ratchet teeth maybe used instead of threaded bolt 518. In an embodiment, the gear 502 iscoupled to the landing 512. In one embodiment, the gear 502 is rotatablycoupled to the landing 512.

The vertically expanding plate 500 includes a throughbore 519 and anupper surface 520. In one embodiment, the vertically expanding plate 500is generally circular in shape. Other suitable configurations of theexpanding plate 500 may also be suitable. In an embodiment, thevertically expanding plate may be generally rectangular in shape withrounded corners, as best seen in FIG. 37. In one embodiment, thevertically expanding plate 500 is flat and generally planar to allowupper surface 520 to engage with the adjacent vertebral body 202.Alternatively, the upper surface 520 can be curved convexly or concavelyto allow for a greater or lesser degree of engagement with the adjacentvertebral bodies. In an exemplary embodiment, the upper surface 520includes texturing 522 to aid in gripping the adjacent vertebral bodies.Although not limited to the following, the texturing can include teeth,ridges, friction increasing elements, keels, or gripping or purchasingprojections.

With reference to FIG. 37, an alternative embodiment of the expandablefusion device 210 of FIGS. 35-36 is shown. In this embodiment, the gear502 is enclosed within the body portion 212 towards the second end 226of the body portion 212 with the vertically expanding plate 500 disposedat or above the upper engagement surface 506 of the body portion 212. Inan embodiment, the vertically expanding plate 500 is positioned towardsthe second end 226 of the body portion 212. While not illustrated, thethreaded bolt 518 extends through the upper engagement surface 506 andcouples the vertically expanding plate 500 and the gear 502. An actuatorscrew 524 extends through the first end 224 of the body portion 212 toengage the gear 502.

The expandable fusion device 210 of FIGS. 35-37 can be inserted in theintervertebral space in a manner similar to that the previouslydescribed with respect to FIGS. 15-20. FIG. 38 illustrates theexpandable fusion device 210 of FIG. 37 between adjacent vertebralbodies 202, 203 in an unexpanded position. After insertion, theexpandable fusion device 210 of FIGS. 35-37 can be expanded into theexpanded position. As previously mentioned, a portion of the fusiondevice shown on FIGS. 35-37 expands vertically in at least onedirection. To partially expand the fusion device 210, the gear 502 canbe rotated in a first direction. An instrument 526 having a gear 528disposed on a distal end 530 of the instrument may be used to rotate thegear 502, as best seen on FIG. 36. In another embodiment, an instrument(not illustrated) may be used to rotate actuation member 524 in a firstdirection. As discussed above, the actuation member 524 is engaged withgear 502; thus, as the actuation member 524 is rotated in firstdirection, the gear 502 rotated in a first direction. The embodimentwith the actuation member 524 is best seen in FIG. 37. As the gear 502rotates, the threaded bolt 518 extends outward from the gear 502, thusextending the laterally expanding plate 500 outward from the bodyportion 212. FIG. 39 illustrates the expandable fusion device 210 ofFIG. 37 in an expanded position.

After expansion, the expandable fusion device 210 can be contracted backto the unexpanded position. The unexpanded position of the fusion device210 is best seen in FIG. 38. To contract the fusion device 210, the gear502 is rotated in a second direction that is opposite the firstdirection. The instrument 526 with the gear 528 may be used to rotatethe gear 502. Alternatively, an instrument may be used to rotate theactuation member 524 to turn the gear 502 in the second direction. Asthe gear 502 rotates in the second direction, the threaded bolt 518retracts pulling the laterally expanding plate 500 inward into theunexpanded position.

Additional Embodiments for the Expandable Fusion Device

In some embodiments, the fusion devices 210 can include additionalfeatures that provide additional benefits such as preventing screwloosening and added stability. These embodiments are discussed below.

FIGS. 40 and 41 show different views of a fusion device 210 including anadvantageous interference nut 610 and stabilization members 622, 624according to some embodiments. The fusion device 210 includes manyfeatures similar to the above-described devices, including a bodyportion 212, a first endplate 214, a second endplate 216, a translationmember 218, and an actuation member 220. The first endplate 214 caninclude a pair of openings 243 a and 243 b through which bone graftmaterial can be received or deposited. Likewise, the second endplate 16can have similar openings, although they are not shown from theillustrated viewpoints. In addition to these features, the fusion device210 includes a novel interference nut 610 that is operably attached to arear section of the body portion 212, as well as a pair of stabilizationmembers 622, 624.

FIG. 40 illustrates an exploded view of the alternative fusion device210, while FIG. 41 shows a top view of the same device with the firstendplate 214 removed. As shown in both views, the translation member 218includes three expansion portions 251, 252, and 254, which are connectedvia bridge portions 256. The expansion portions 251, 252, and 254 eachhave angled surfaces that are configured to engage grooved portions ofthe first and second endplates 214 and 216. In some embodiments, theangled surfaces are of similar angles, while in other embodiments, theangled surfaces are of different angles. Advantageously, by providing atleast three expansion portions 251, 252 and 254, this allows for an evenexpansion along a majority of the length of the body portion 212 of thefusion device 210.

The translation member 218 is received in the central opening of thebody portion 212. The body portion 212 can include a first end 224 and asecond end 226. In some embodiments, the first end 224 includes one ormore apertures 602, 604 as shown in FIGS. 40 and 41. These apertures602, 604 advantageously receive one or more stabilization members 622,624.

In some embodiments, the stabilization members 622, 624 each include afirst substantially smooth portion 632, 634 and a second threadedportion 634, 644. The stabilization members 622, 624 can be insertedthrough the apertures 602, 604 of the body portion 212, with thethreaded portions 634, 644 serving as the leading end that enters theapertures. After passing through the apertures 602, 604 of the bodyportion 212, the stabilization members 622, 624 can come into contactwith a side of the translation member 218. In some embodiments, thethreaded portions 634, 644 of the stabilization members 622, 624 can bethreaded into mateable threaded surfaces of the translation member 218.Advantageously, by using a pair of stabilization members 622, 624 asshown in FIGS. 40 and 41 on a first end of the body portion 212, thisserves to prevent rocking of the body portion 212 during expansion andcontraction of the device 210.

While the illustrated embodiment in FIGS. 40 and 41 show a pair ofstabilization members 622, 624, in other embodiments, a singlestabilization member or more than two stabilization members can be usedto assist in preventing rocking of the body portion 212. In addition,while the stabilization members 622, 624 are illustrated as having asubstantially cylindrical surface section, in other embodiments, thestabilization members 622, 624 can assume other shapes and geometries.For example, in other embodiments, the stabilization members 622, 624can have a surface that includes at least one edge or corner.

As shown in FIGS. 40 and 41, the body portion 212 also includes aninterference nut 610 that is positioned within a rear section of thebody portion 212. In some embodiments, the interference nut 610 isseparate and removable from the body portion 212, while in otherembodiments, the interference nut 610 is not removable from the bodyportion 212. In some embodiments, the interference nut 610 comprises asquare nut that is operably connected to a rear section of the bodyportion 212. The interference nut 610 can be mateably connected to arear of the body portion 212, for example, via a dove-tail type cut thatencapsulates the interference nut. The interference nut 610 can beadvantageously formed of a biocompatible material. In some embodiments,the interference nut 610 is formed of PEEK.

The interference nut 610 can include a hole (not shown) that is capableof receiving the actuation member 220 therethrough. The actuation member220, which can comprise a threaded set screw, passes through theinterference nut 610 and into contact with the translation member 218,as best shown in FIG. 41. Advantageously, the interference nut 610serves to add drag to the actuation member 220 as it passestherethrough, thereby establishing an interference fit. By providing aninterference fit, the risk of the actuation member 220 being loosenedprior to or during use is minimized.

FIGS. 42-44 show different views of an alternative fusion device 210including novel side stabilization members 652, 654 and a low profileactuation member 220. The fusion device 210 includes many featuressimilar to the above-described devices, including a body portion 212, atranslation member 218, and an actuation member 220. The fusion device210 can also include a first endplate 214 and a second endplate 216 forcontacting vertebral surfaces, as best shown in FIG. 44. Both the firstendplate 214 and second endplate 216 can include a pair of openingsthrough which bone graft material can be received or deposited. Inaddition to these features, the fusion device 210 includes novel sidestabilization members 652, 654 that are introduced through side slots213 and 214 of the body portion 212. The fusion device 210 also includesa configuration that allows the actuation member 220 to be of lowprofile, as shown in FIG. 42.

FIG. 42 illustrates a top view of the alternative fusion device 210having side stabilization members with the first endplate 214 removed,while FIG. 43 illustrates a perspective view of the same device. FIG. 44illustrates a side cross-sectional view of the alternative fusion device210 having side stabilization members. As shown in all three views, thetranslation member 218 includes three expansion portions 251, 252, and254, which are connected via bridge portions 256. The expansion portions251, 252, and 254 each have angled surfaces that are configured toengage grooved portions of the first and second endplates 214 and 216.In some embodiments, the angled surfaces are of similar angles, while inother embodiments, the angled surfaces can be of different angles.Advantageously, by providing at least three expansion portions 251, 252and 254, this allows for an even expansion along a majority of thelength of the body portion 212 of the fusion device 210.

The translation member 218 is received in the central opening of thebody portion 212. The body portion 212 can include sidewalls that extendbetween the first end 224 and a second end 226. As shown in FIG. 43,each of the sidewalls can include side slots 213, 214 for receiving oneor more side stabilization members 652, 654.

In some embodiments, the side stabilization members 652, 654 are similarto the stabilization members 622, 624 (shown in FIG. 40). That is, theside stabilization members 652, 654 can include a threaded portion and asubstantially smooth portion. The side stabilization members 652 can beinserted through the side slots 213, 214 of the body portion 212 and canoperably attach (e.g., via threads) to the translation member 218.Advantageously, the side slots 213, 214 help to provide rotationalstability to the translation member 218 relative to the body portion 212prior to or during use of the fusion device 210.

In addition to providing side stabilization members, the fusion device210 provides a configuration that includes a low profile actuationmember 220. Advantageously, as shown in FIG. 42, the actuation member220 (which can comprise a screw) can have a head portion that issubstantially flush against the surface of the body portion 212, while adistal portion 221 of the actuation member 220 can extend through a wallof the translation member 218.

As shown in FIG. 44, in some embodiments, the actuation member 220 cancomprise a set screw 772 accompanied by a flange 773 and an actuationelement 774. The set screw 772 and actuation element 774 can both bethreaded. Upon rotation of the set screw 772, the actuation element 774is threaded forward, thereby pushing the first endplate 214 upwardly andthe second endplate 216 downwardly to cause expansion of the actuationmember 220. The flange 773, which can be cylindrical, advantageouslyresists the opposing forces as the actuation element 774 is threadedforward, thereby helping to keep the fusion device 210 in an expandedconfiguration. Upon reverse rotation of the set screw 772, the fusiondevice 210 can collapse. As shown in FIG. 44, a blocking nut 771 can beprovided that is threaded onto the back side of the set screw 772 tosecure the set screw into place when the device 210 is collapsed.

Additional embodiments of an expandable fusion device 210 are shown inFIGS. 49 and 50. This fusion device 210 incorporates a ring member 802into a pocket 820 formed in the translation member 218.

The fusion device 210 in FIGS. 49 and 50 include many features similarto the above-described devices, including a body portion 212, a firstendplate 214, a second endplate 216, a translation member 218, anactuation member 220, and a pin member 290. The first endplate 214 caninclude one or more openings through which bone graft material can bereceived or deposited. Likewise, the second endplate 216 can havesimilar openings, although they are not shown from the illustratedviewpoints. The translation member 218 can be comprised of one or moreramped expansion portions, such as expansion portions 251 and 252, whichare configured to assist in expansion and contraction of the fusiondevice 210, as discussed above.

In addition to these features, the fusion device 210 incorporates a ringmember 802 that is positioned between the actuation member 220 and thetranslation member 218. In some embodiments, the ring member 802 isreceived in a pocket 820 that is formed in one of the expansion portions(such as expansion portion 251) of the translation member 218. As shownin FIG. 50, the ring member 802 can comprise a closed annular body thatcan be received in a similarly shaped recess 820 formed in the body ofan expansion portion 251 of the translation member 218. Each ofexpansion portion 251, ring member 802 and actuation member 220 can beplaced over a pin member 290.

In some embodiments, the ring member 802 can be formed of a materialthat is different from the translation member 218 and/or actuationmember 220. For example, while in some embodiments the translationmember 18 and/or actuation member 220 are comprised of a metal, such asa biocompatible stainless steel, titanium or metal alloy, the ringmember 802 can be formed of a polymer such as polyether ether ketone(PEEK). The advantage of providing a PEEK ring member 802 is that a morelubricious material is positioned between the face of the actuationmember 220 and the surface of the translation member 218, therebyreducing the friction between the two parts. With the PEEK ring member's802 reduced coefficient of friction, this increases the amount of forcetransmitted when the actuation member 220 is screwed into thetranslation member 218, thereby increasing the amount of expansion forceprovided to the ramped translation member 218. In some embodiments, theuse of a PEEK ring member between the interface of the actuation member220 and translation member 218 increases the expansion force of theramped translation member 218 while using the same force as would beapplied if the PEEK ring member was not in place. In some embodiments,the use of a PEEK ring member between the translation member 218 andactuation member 220 provides a buffer that can prevent galling thatwould occur due to metal-on-metal contact between the translation memberand actuation member.

In some embodiments, rather than receive an insert in the shape of ringmember 802, the translation member 218 can receive an insert having adifferent shape. For example, the translation member 218 can include oneor more recesses that accommodate a wedge-shaped PEEK member between thetranslation member 218 and the actuation member 220. Like the ringmember 802, the wedge-shaped PEEK member can also serve as a lubriciousmaterial that reduces the friction between the translation member 218and the actuation member 220.

In addition, in some embodiments, an insert can be placed between thetranslation member 218 and actuation member 220 without having to form arecess in the translation member. For example, a PEEK washer can beprovided between the interface of the translation member 218 andactuation member 220.

Although the preceding discussions only discussed having a single fusiondevice 210 in the intervertebral space, it is contemplated that morethan one fusion device 210 can be inserted in the intervertebral space.It is further contemplated that each fusion device 210 does not have tobe finally installed in the fully expanded state. Rather, depending onthe location of the fusion device 210 in the intervertebral disc space,the height of the fusion device 210 may vary from unexpanded to fullyexpanded.

Trial Member

In some embodiments, the fusion devices 210 can be put into place withthe assistance of a novel expandable trial member. The expandable trialmember can be used prior to inserting an expandable fusion device inbetween vertebral bodies to obtain an accurate size measurement for thefusion device. The expandable trial member can help a user determine afusion device of an appropriate size to use in a vertebra.Advantageously, the novel expandable trial member disclosed herein isconfigured such that the amount of distraction force applied to thetrial member is linear and constant over its entire expansion range.

FIGS. 45-48 show different perspectives of an expandable trial memberaccording to some embodiments. FIG. 45 illustrates a perspective view ofthe trial member in a non-expanded configuration. FIG. 46 illustrates aside cross-sectional view of the trial member in an expandedconfiguration. FIG. 47 illustrates a top view of the trial member. FIG.48 shows an exploded view of the trial member.

As shown in the figures, the expandable trial member 700 comprises abody portion 712, an upper endplate 714, a lower endplate 716, atranslation member 718 and an actuation member 720. The trial member 700is configured such that when the actuation member 720 (shown in FIG. 46)is pulled in a backward or proximal direction toward a handle portion782 (shown in FIG. 47), inner shaft or rod member 722 (shown in FIG. 46)will push forward and cause inner ramped surfaces of the translationmember 718 to translate relative to inner angled grooves cut into theupper endplate 714 and/or lower endplate 716, thereby causing expansionof the trial member 700. When the actuation member 720 is pushed in aforward or distal direction away from the handle portion 782, the trialmember 700 can collapse. In other embodiments, distal movement of theactuation member 720 can result in expansion of the expandable trialmember, while proximal movement of the actuation member 720 can resultin collapse of the trial member. The configuration of the trial member700 thus allows pushing and pulling of the actuation member 720 toactuate the shaft or inner rod 722, thereby causing expansion orcontraction of the trial member 700. Advantageously, because movementalong the ramped surfaces of the upper endplate 714 and lower endplate716 cause expansion or contraction, the amount of distraction force islinear over the entire expansion range of the trial member 700.

The expandable trial member 700 includes an upper endplate 714 and alower endplate 716. As shown best in FIG. 46, both the upper endplate714 and lower endplate 716 can include one or more surface grooves 780.While the trial member 700 need not remain over an extended period oftime within a vertebra, the surface grooves 780 advantageously help toretain the trial member 700 within a vertebra during its operationaluse.

A body portion 712 can be placed in between the upper endplate 714 andlower endplate 716. The body portion 712 can include a sloped orchamfered anterior portion 734 (shown in FIG. 45) that assists indistraction of vertebral bodies.

Within the body portion 712, the translation member 718 can be receivedtherein. As shown best in FIG. 48, the translation member 718 includes aplurality of upper ramped surfaces 751, 752 and 754 and a plurality oflower ramped surfaces 756, 757 and 758. As shown in FIG. 45, the upperand lower endplates 714 and 716 can include one or more holes 711 thataccommodate the upper and lower ramped surfaces when the trial member700 is in a closed configuration. The upper ramped surfaces and lowerramped surfaces are configured to slidably mate with correspondinggrooves (such as upper grooves 746 and 748 and lower groove 749 shown inFIG. 46). When the actuation member 720 is pulled distally, the upperramped surfaces slide downwardly through the grooves and the lowerramped surfaces slide upwardly through the grooves, thereby causing theexpandable trial member 700 to expand from its closed configuration,shown in FIG. 45, to an expanded configuration, shown in FIG. 46.

In some embodiments, the body portion 712 can include a pair of sideslots 713, as shown in FIG. 45. The side slots 713 are configured toeach receive a side stabilization member 762. In some embodiments, thestabilization members 762 comprise stabilizer screws that contact thetranslation member 718. Advantageously, the stabilization members 762help keep the translation member 718 centered inside the body portion712 to prevent twisting as it translates forward and backwards.

In some embodiments, the trial member 700 is configured to expand tohave a trial height that is at least fifty percent higher than a heightof the trial member 700 in its closed configuration. In otherembodiments, the trial member 700 is configured to expand to have atrial height that is at least two times the height of the trial member700 in its closed configuration. By having a trial member 700 with awide variety of expansion configurations, a user can advantageouslychoose a properly sized fusion implant to accommodate a number ofdifferent patients of different sizes.

FIGS. 51-55 show different views of some embodiments of a proximalportion 750 of a trial member 700. In some embodiments, the trial member700 can be a single piece that extends from a proximal end to a distalend. In other embodiments, which are reflected in FIGS. 51-55, theproximal portion 750 can comprise a removable handle portion 782 that isconfigured to operably attach to a body of the trial member 700.Advantageously, by providing a removable handle portion 782, this helpsto facilitate easier cleaning of the trial member 700. The proximalportion 750 is configured to assist in movement of the inner shaft 722of the trial member, thereby causing expansion and contraction of thetrial member upper and lower endplates. In addition, the proximalportion 750 can comprise a novel locking member that operably mates theproximal portion 750 to the inner shaft 722, thereby allowing the innershaft 722 to be pulled back. Once the upper and lower endplates of thetrial member are separated a desired distance, the trial member 700 canbe removed, and an appropriately sized expandable implant can beinserted based on the separation distance between the upper and lowerendplates.

In the trial member 700 shown in FIG. 51, the removable proximal portion750 is configured to operably attach to a body of the trial member (suchas shown in FIG. 47). The proximal portion 750 is comprised of a handle782 in the form of a housing member, a removable engagement insert 816,and a slidable locking member 740. The interior of the proximal portion750 is configured to have a threaded insert 816 that mates with anexterior threaded surface 724 along the body of the trial member 700. Asthe proximal portion 750 is rotatably threaded onto the body portion, asurface of the slidable locking member 740 pushes against the innershaft 722 (shown in FIG. 53 as within the exterior threaded surface724), thereby causing expansion of the trial member endplates.

The body of the handle portion 782 is configured to receive a threadedinsert 816 therein. While in some embodiments, the threaded insert 816is comprised of the same material as the exterior threaded surface 724of the body, in other embodiments, the threaded insert 816 and threadedsurface 724 are of different materials. For example, in someembodiments, the threaded insert 816 can be a polymer, such as PEEK,while the exterior threaded surface 724 can be a metal, such asstainless steel. One skilled in the art will appreciate that othermaterials can also be used. By providing a PEEK insert 816 that threadsonto the metal threads, this advantageously reduces the friction betweenthe two components, thereby reducing the amount of work that is absorbedby the two components and increasing the expansion forces transmitted tothe endplates. In addition, the use of a threaded PEEK insert 816 onmetal prevents thread galling over multiple uses under high loading. Toprevent rotation of the insert 816, pin members 826 can be provided tocontact the surface of the insert 816 along with the inner wall of thehandle portion 782 (as shown in FIG. 54). As shown in FIG. 55, aplurality of pin members 826 can be provided that align with thelongitudinal axis of the insert 816 to prevent rotation of the insert816.

As the insert 816 of the removable proximal portion 750 is rotatablythreaded onto the exterior threads of the body of the trial member, asurface of the slidable locking member 740 pushes against the innershaft 722 of trial member, thereby causing expansion of the endplates.Reverse rotation of the threads of the insert 816 will result incontraction of the endplates. In some embodiments, the slidable lockingmember 740 can be moved from an unlocked to a locked configuration suchthat the inner shaft 722 is operably mated with the proximal portion 750via the locking member 740. More details regarding the slidable lockingmember 740 are discussed below.

FIG. 39 illustrates the proximal portion 750 of the trial member withthe slidable locking member 740 in an unlocked configuration, while FIG.54 illustrates the proximal portion 750 of the trial member with theslidable locking member 740 in a locked configuration. In the unlockedconfiguration, the proximal portion 750 is able to translate along thebody of the trial member, thereby pushing on the inner shaft 722 andcausing expansion of the trial member endplates. In the lockedconfiguration, the proximal portion 750 is operably mated to the innershaft 722, thereby allowing the inner shaft 722 to be pulled back viathe proximal portion 750 in situ.

The slidable locking member 7540 comprises an insert attached to theproximal portion 750 of the trial member. In some embodiments, thelocking member 740 comprises a J-shaped or hook-shaped body that isconfigured to slide up and down in order to provide unlocked and lockedconfigurations, as shown in FIGS. 51 and 52 respectively. The body ofthe locking member 740 can include a nub 749 (identified in FIGS. 53 and54) that can be received in a snap-fit into corresponding grooves 751 aand 751 b formed in the proximal portion 750. When the nub 749 is ingroove 751 a, the locking member 740 is in an unlocked configuration.When the nub 749 is in groove 751 b, the locking member 740 is in alocked configuration.

As shown in FIG. 54, the hook-shaped body of the locking member 740 alsoincludes a mating end 747 that can be received in a complementary matingportion 723 of the inner shaft 722. When the mating end 747 is receivedin the mating portion 723 of the inner shaft 722, this advantageouslymates the proximal portion 750 to the inner shaft 722, thereby allowingthe inner shaft 722 to be pulled back in situ if desired.

In some embodiments, the locking member 740 is of the same material assurfaces of the proximal portion 750 and/or the inner shaft 722. Inother embodiments, the locking member 740 is of a different materialfrom surfaces of the proximal portion 750 and/or the inner shaft 722.For example, the locking member 740 can be formed of a polymer such asPEEK, while an adjacent surface of the proximal portion 750 is a metalsuch as stainless steel. By providing a locking member 740 that is of alubricious material such as PEEK, this advantageously reduces thefriction between the locking member 740 and adjacent surfaces, therebyresulting in less galling between adjacent surfaces.

Various methods are provided for utilizing fusion devices and trialmembers are provided. In some embodiments, a cavity is formed in avertebral space between two vertebrae. An expandable trial memberincluding a first endplate, a second endplate, a translation member withramped surfaces, a body portion and an actuation member can be provided.In an unexpanded form, the trial member can be introduced into thevertebral space. Once in the vertebral space, the actuation member canbe rotated, thereby causing expansion of the first endplate and secondendplate via motion of the translation member. With the trial member inthe vertebral space, an assessment can be made as to the proper size ofan expandable fusion device.

Once the trial member is removed, an expandable fusion device comprisinga first endplate, a second endplate, a translation member with rampedsurfaces, a body portion and an actuation member can be provided.Optionally, the trial member can include an interference nut that isattached to a rear section of the body portion, one or more front orside stabilization members, a flange, a blocking nut, or combinationsthereof. The expandable fusion device can be inserted into the vertebralspace in an unexpanded form. Once in the vertebral space, the actuationmember of the fusion device can be rotated, thereby causing expansion ofthe first endplate and second endplate via motion of the translationmember. Once in its expanded form, the fusion device is kept in placeand can remain in the vertebral space for an extended period of time.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

What is claimed is:
 1. A surgical system comprising: a first endplate; asecond endplate; a body portion positioned between the first endplateand the second endplate, wherein the body portion includes a proximalportion, a distal portion, a first sidewall that extends between theproximal portion and the distal portion, and a second sidewall thatextends between the proximal portion and the distal portion, wherein theproximal portion includes an opening for receiving an actuation membertherethrough, wherein rotation of the actuation member causes a distanceof separation to increase between the first endplate and the secondendplate; and wherein the distal portion includes a first aperture forreceiving a first stabilization member and a second aperture forreceiving a second stabilization member.
 2. The system of claim 1,wherein at least one of the first stabilization member and the secondstabilization member comprises an elongate body comprising a smoothportion and a threaded portion.
 3. The system of claim 1, furthercomprising a translation member received within the body portion.
 4. Thesystem of claim 3, wherein rotation of the actuation member causestranslation of the translation member.
 5. The system of claim 3, whereinthe translation member comprises a first expansion portion and a secondexpansion portion separated by a bridge.
 6. The system of claim 5,wherein the translation member further comprises a third expansionportion, wherein the third expansion portion is separated from thesecond expansion portion by a bridge.
 7. The system of claim 1, whereinthe first stabilization member is positioned closer to the firstsidewall than the second sidewall, and the second stabilization memberis positioned closer to the second sidewall than the first sidewall. 8.The system of claim 1, further comprising a first side stabilizer thatextends through a first slot in the first sidewall of the body portionand a second side stabilizer that extends through a second slot in thesecond sidewall of the body portion.
 9. The system of claim 1, furthercomprising a translation member received within the body portion,wherein the translation member includes a first ramped surface and asecond ramped surface, wherein the first ramped surface and the secondramped surface are angled in the same direction.
 10. The system of claim1, further comprising a translation member received within the bodyportion, wherein the translation member includes a first ramped surfaceand a second ramped surface, wherein the first ramped surface is a fixeddistance away from the second ramped surface.
 11. A surgical systemcomprising: a first endplate; a second endplate; a body portionpositioned between the first endplate and the second endplate, whereinthe body portion includes a proximal portion, a distal portion, a firstsidewall that extends between the proximal portion and the distalportion, and a second sidewall that extends between the proximal portionand the distal portion, wherein the proximal portion includes an openingfor receiving an actuation member therethrough, wherein rotation of theactuation member causes a distance of separation to increase between thefirst endplate and the second endplate; and wherein the first sidewallincludes a first slot for receiving a first side stabilization membertherethrough and the second sidewall includes a second slot forreceiving a second side stabilization member therethrough.
 12. Thesystem of claim 1, wherein the first endplate comprises a first openingand a second opening extending therethrough.
 13. The system of claim 1,further comprising a translation member received within the bodyportion, wherein the translation member includes at least one rampedsurface for contacting the first endplate and at least one rampedsurface for contacting the second endplate.
 14. The system of claim 13,wherein the translation member includes at least two ramped surfaces forcontacting the first endplate and at least two ramped surfaces forcontacting the second endplate.
 15. The system of claim 13, furthercomprising an interference nut positioned between the body portion andthe translation member.
 16. The system of claim 15, wherein theinterference nut is formed of a different material from the body portionand the translation member.
 17. The system of claim 16, wherein theinterference nut is formed of PEEK.
 18. The system of claim 11, whereinthe distal portion includes a first aperture and a second aperture forreceiving a first stabilization member and a second stabilizationmember.
 19. The system of claim 11, wherein the first side stabilizationmember and the second side stabilization member are each threaded. 20.The system of claim 11, further comprising a translation member receivedwithin the body portion, wherein rotation of the actuation member causeslinear translation of the translation member.